U.S. patent number 6,539,656 [Application Number 09/754,636] was granted by the patent office on 2003-04-01 for luminaire and light-emitting panel.
This patent grant is currently assigned to Koninklijke Philips Electronics N.V.. Invention is credited to Theodorus Mattheus Maria Maas, Constance J. E. Saalberg-Seppen, Jelle Hilbrand Schuurmans, Edwin Van Lier.
United States Patent |
6,539,656 |
Maas , et al. |
April 1, 2003 |
Luminaire and light-emitting panel
Abstract
A luminaire comprises a relatively thin and flat light-emitting
panel (1) having a light-emitting window (2) and, opposite said
light-emitting window, a rear wall (3) with opposed edge surfaces
(4, 14). At least one of the edge surfaces (4) is light
transmitting and associated with a plurality of light sources (5,
5', 5", . . . ). Light originating from the light sources (5, 5',
5", . . . ) is spread in the panel (1). The invention is
characterized in that a plurality of deformities (7, 7', 7", . . .
; 8, 8', . . . ) is provided in the panel (1) for extracting light
from the panel (1) via the light emission window (2). The
deformities (7, 7', 7", . . . ; 8, 8', . . . ) are clustered so as
to form at least one light symbol (27; 28). The configuration of
the clusters (17; 18) of deformities (7, 7', 7", . . . ; 8, 8', . .
. ) corresponds to the shape of the light symbol (27; 28).
Preferably, the luminaire has a first and a second
light-transmitting edge surface, with respectively, a first and a
second plurality of light sources being associated with said
surfaces. A first cluster of deformities only couples light from
the first light source out of the panel, thereby forming a first
light symbol, while a second cluster of deformities only couples
light from the second light source out of the panel, thereby
forming a second light symbol, independently of the formation of
the first light symbol. The luminaire according to the invention
provides independent lighting and coloring possibilities of light
symbols in a single-panel luminaire.
Inventors: |
Maas; Theodorus Mattheus Maria
(Eindhoven, NL), Schuurmans; Jelle Hilbrand
(Eindhoven, NL), Saalberg-Seppen; Constance J. E.
(Arnhem, NL), Van Lier; Edwin (Eindhoven,
NL) |
Assignee: |
Koninklijke Philips Electronics
N.V. (Eindhoven, NL)
|
Family
ID: |
26071708 |
Appl.
No.: |
09/754,636 |
Filed: |
January 4, 2001 |
Foreign Application Priority Data
|
|
|
|
|
Jan 6, 2000 [EP] |
|
|
00200028 |
Apr 6, 2000 [EP] |
|
|
00201253 |
|
Current U.S.
Class: |
40/546 |
Current CPC
Class: |
G02B
6/0036 (20130101); G02B 6/006 (20130101); G02B
6/0068 (20130101); G02B 6/0091 (20130101); G09F
13/18 (20130101); G09F 19/12 (20130101); F21Y
2105/00 (20130101); F21Y 2115/10 (20160801) |
Current International
Class: |
F21V
8/00 (20060101); G09F 13/18 (20060101); G09F
19/12 (20060101); G09F 013/18 () |
Field of
Search: |
;40/546 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
3833315 |
|
Apr 1990 |
|
DE |
|
0945674 |
|
Sep 1999 |
|
EP |
|
Primary Examiner: Davis; Cassandra H.
Attorney, Agent or Firm: Keegan; Frank
Claims
What is claimed is:
1. A luminaire comprising a panel of a light-transmitting material,
said panel including a light emission window, a rear wall opposite
said light emission window and edge surfaces which are situated
between the light emission window and the rear wall, at least one
first edge surface of the panel being light transmitting, at least
one first light source being associated with the at least one first
edge surface, and in operation, light originating from the at least
one first light source being incident on the at least one first
edge surface and spreading in the panel, wherein in the panel a
plurality of deformities are provided for coupling light out of the
panel via the light emission window, said deformities being
clustered so as to form at least one first cluster of deformities,
and said at least one first cluster having a configuration which
corresponds to a shape of a first light symbol, and wherein at
least one second edge surface is light-transmitting, at least one
second light source being associated with the at least one second
edge surface, in operation, the at least one first cluster of
deformities coupling out light originating from the at least one
first light source to form the first light symbol, and in
operation, a second cluster of deformities coupling out light
originating from the at least one second light source to form a
second light symbol.
2. A luminaire as claimed in claim 1, wherein the at least one
first cluster and the second cluster comprise at least one
deformity which is a triangular prism, a side face of the prism
being provided transversely to the rear wall, if the at least one
deformity forms part of the at least one first cluster, ribs of the
prism extend transversely to the direction wherein, in operation,
the at least one first light source emits light, and if the at
least one deformity forms part of the second cluster, ribs of the
prism extend transversely to the direction wherein, in operation,
the at least one second light source emits light.
3. A luminaire as claimed in claim 1, wherein the at least one
first light source comprises a light-emitting diode.
4. A luminaire as claimed in claim 3, wherein the light-emitting
diode comprises a luminous flux of at least 5 lm.
5. A luminaire having a panel, said panel comprising: a light
emission window, a rear wall opposite said light emission window, a
first edge surface for receiving first light rays, and a second
edge surface for receiving second light rays, said first edge
surface and said second edge surface being situated between said
light emission window and said rear wall, wherein said light
emission window or said rear wall includes first deformities which
are clustered to form a first light symbol upon incidence of said
first light rays, and wherein said light emission window or said
rear wall includes second deformities which are clustered to form a
second light symbol upon incidence of said second light rays.
Description
BACKGROUND OF THE INVENTION
The invention relates to a luminaire comprising a panel of a
light-transmitting material, which panel includes a light emission
window, a rear wall opposite said light emission window and edge
surfaces which are situated between the light emission window and
the rear wall, at least one of the edge surfaces of the panel being
light transmitting, at least one light source being associated with
the light-transmitting edge surface, and in operation, light
originating from the light source being incident on the
light-transmitting edge surface and spreading in the panel.
The invention further relates to a light-emitting panel for use in
the luminaire.
Such luminaires are known per se and are also referred to as edge
lighting systems. They are applied, inter alia, in so-called
luminous signs, among other things, for advertising purposes. They
can also be used in guiding boards, such as "exit"-signs, in
billboards, traffic lights, systems for guiding traffic flows and
as (dashboard) lighting in vehicles. Said luminaires are further
used as back lighting, for example, for display devices, such as
LCD-devices. Said luminaires are used both as interior lighting and
exterior lighting.
In such luminaires, a tubular low-pressure mercury-vapor discharge
lamp, for example a (compact) fluorescent lamp (TL), is generally
used as the light source, and the light emitted, in operation, by
said light source is coupled into an optical waveguide which
generally forms a relatively thin and flat panel, which panel is
made, for example, of a synthetic resin or glass, and light being
transported through the panel under the influence of total internal
reflection. A text or a logo, for example a brand name, is engraved
in the optical waveguide, the engraving lighting up, in operation,
as a diffuse luminous area. The engraving is formed, for example,
by etching or by suitably providing scratches. A text or a logo may
alternatively be provided by applying a (light-scattering) layer on
the panel. A text or a logo may alternatively be provided on a tape
applied to the panel, which tape may exhibit differences in
refractive index.
Such a luminaire may also be provided with an alternative light
source in the form of a plurality of opto-electronic elements, also
referred to as electro-optic elements, such as electroluminescent
elements, for example light-emitting diodes (LEDs). These light
sources are generally provided so as to be close to or abut against
a light-transmitting edge surface of the panel, so that, in
operation, light originating from the light source is incident on
the light-transmitting edge surface and spreads into the panel.
From DE-A 38 33 315 an LED edge lighting system is known, which
comprises one or more light-emitting diodes which are coupled via
optical waveguides to a light-emitting panel to cause a light
surface or light symbol provided in or on the light emission window
to light up. This light surface or light symbol is provided as a
light-scattering layer on the surface of the panel, or as a
light-scattering recess in the surface of the panel.
A luminaire of the type mentioned above has various drawbacks. For
example, only a part of the light in the panel contacting the light
symbol is coupled out of the panel, and, in addition, a part of the
light is emitted in the direction of the rear wall. Besides, the
light symbol lights up like a diffusely luminescent area. As a
result, the attractiveness of the luminaire is reduced.
SUMMARY OF THE INVENTION
It is an object of the invention to obviate the above drawbacks.
The invention more particularly aims at providing a luminaire of
the type mentioned in the opening paragraph, in which light is
coupled out so as to obtain a specific light distribution.
To achieve this, the luminaire is characterized in accordance with
the invention in that in the panel a plurality of deformities is
provided for coupling light out of the panel via the light emission
window, said deformities being clustered so as to form at least one
light symbol, and said cluster having a configuration which
corresponds to the shape of the light symbol.
The measure in accordance with the invention causes the attractive
effect, the appeal and the attention value of the luminaire in
accordance with the invention to be increased. The term
"deformities" is to be taken to mean, in general, in the
description and the claims of the current invention, means by means
of which light can be coupled out of the panel. A deformity is an
optical structure having a predetermined geometrical shape and
dimensions. The use of deformities enables light to be coupled out
of the panel in a well-defined manner. The light is coupled out in
a predetermined direction, which direction may also depend upon the
shape and the position of the deformity on the panel. This means,
inter alia, that an observer who moves past the luminaire without
specifically looking in the direction of the panel is struck at a
certain moment "from the corner of his eye" by light emitted by the
luminaire in accordance with the invention. This unexpected
occurrence arouses the attention of the observer and "forces" as it
were the observer to look at the luminaire. This results in an
increase of the attention value of the luminaire.
The deformities serve as a secondary light source.
An additional advantage of these deformities is that clusters of
deformities can be selectively illuminated. By virtue thereof, it
becomes possible to make different light symbols light up
independently from each other and/or sequentially. By making light
symbols light up alternately, using control electronics, by causing
the clusters of deformities associated therewith to couple light
out of the panel, light objects that move as it were can be
obtained (for example a man who seems to be walking), or a text can
be made visible by making the letters light up one after the other.
Also various, colored light sources can be alternately switched on
and off, so that a light symbol lights up in various colors. In
this manner, the luminaire in accordance with the invention obtains
dynamic lighting possibilities with a high attention value.
A further advantage of these deformities is that more light is
coupled out of the panel, which leads to a directed reflection of
these deformities and hence an improved brightness of the
luminaire. To direct the light which is coupled out of the panel by
these deformities, preferably, a boundary surface of the
deformities is provided with a specularly reflecting surface, for
example a reflecting layer of aluminium or silver, or a reflective
multilayer coating. In an alternative, preferred embodiment, the
deformities are shaped such that, in the deformities, total
internal reflection causes the light to be coupled out of the
panel. An important advantage of total internal reflection as a way
of coupling light out of the panel is that it is not necessary to
locally provide the deformities with a reflecting surface.
In the known luminaire, light incident on the diffusely reflecting
light symbol when being reflected to and fro in the panel is
emitted in all directions, for example also in the direction of the
rear wall. As a result, the brightness of the luminaire in a
direction transverse to the panel is lower than that of the light
source, leading to a reduction of the attractiveness of the
luminaire.
It is to be noted that the provision of a plurality of deformities
to couple light out of a luminaire is known per se. In such edge
lighting systems, a plurality of light-extracting so-called
"deformities" or "disruptions" are provided in the light-emitting
panel. The shape and/or dimensions of these deformities may change
gradually and/or the distance between the deformities in the panel
may change gradually. However, the objective of such edge lighting
systems is to obtain a light distribution which is as uniform as
possible, said systems serving, in particular, as a lighting panel
for, for example, (flat) display devices, such as, for example,
liquid crystal display devices. The light distribution of the
luminaire in accordance with the invention deliberately is not
homogenous and not uniform. These (dynamic) deviations from a
homogeneously and uniformly illuminated panel add to the attention
value of the luminaire.
A preferred embodiment of the luminaire is characterized in
accordance with the invention in that at least a first and a second
edge surface are light-transmitting, at least one first light
source being associated with the first light-transmitting edge
surface, and at least one second light source being associated with
the second light-transmitting edge surface, and in operation, a
first cluster of deformities coupling out light originating from
the first light source to form a first light symbol, and in
operation, a second cluster of deformities coupling out light
originating from the second light source to form a second light
symbol.
In the known luminaire, at a specific location on the panel only
one specific light symbol (for example the letter "P") can be made
to light up or a collection of light symbols (for example the words
"ACCESS DENIED") can be made to light up simultaneously. In the
above-mentioned embodiment of the luminaire in accordance with the
invention, two light symbols (for example the letter "E" and the
letter "A") or two collections of light symbols (for example the
word "EXIT" and the words "NO ENTRY") can be made to light up on
the panel independently of each other. In addition, these light
symbols or collections of light symbols can locally overlap
entirely or partly. Thus, in this embodiment it is possible to
switch from one text to the other text. It is also possible to add
text to an existing text (for example by replacing the term "ENTRY"
by "NO ENTRY"), or by providing a brand name or logo with a crown
or with symbols in the form of, for example, stars, which
additional light symbols can be switched on and switched off,
depending on the requirements.
It is further possible in this embodiment of the luminaire in
accordance with the invention that two light symbols or two
collections of light symbols have different colors (for example a
text or brand name which lights up in green and/or in blue, above
which there is a star and/or a crown which lights up in red and/or
yellow). By coupling out light by associating a first cluster of
deformities with a first light source, and by coupling out light by
associating a second or further cluster of deformities with a
second or further light source, the number of lighting
possibilities is increased substantially and the attractive value
of the luminaire in accordance with the invention is substantially
increased. In general, a plurality of panels whose light emission
windows are arranged, for example, parallel to each other are
necessary to make seemingly overlapping light symbols light up
independently of each other. Such stacks of panels take up too much
space, require much material, are relatively heavy and large and
hence expensive.
To make sure that the light is coupled out of the panel so as to
travel in (a) specific direction(s), the deformities are preferably
arranged in the rear wall of the panel. If light, which is
reflected to and fro by the panel, is incident on such a deformity
or optical structure in the rear wall, reflection occurs, causing
light to be sent towards the light emission window and leave the
panel at the light emission window. In an alternative embodiment,
the deformities are provided in or on the light emission window of
the panel. These deformities may have, for example, a lens
structure.
The shape, dimensions and location of the deformities influence the
way in which light leaves the panel. For example, a preferred
embodiment of the luminaire in accordance with the invention is
characterized in that the shape of the deformity is selected from
the group formed by a triangular prism, a tetrahedron, a
quadrilateral pyramid and a cone. Such shapes are very suitable for
coupling light out of the luminaire in various ways.
A deformity in the form of a triangular prism can very suitably be
used to allow unobstructed passage of light in one direction and
couple said light out of the panel in a direction transverse
thereto. A favorable embodiment of the luminaire in accordance with
the invention is characterized in that the deformity is a
triangular prism, a side face of the prism being provided
transversely to the rear wall, if the deformity forms part of the
first cluster of deformities, ribs of the prism extend transversely
to the direction wherein, in operation, the first light source
emits light, and if the deformity forms part of the second cluster
of deformities, ribs of the prism extend transversely to the
direction wherein, in operation, the second light source emits
light.
In this embodiment, the triangular prisms are situated with a side
face on or in the rear wall of the panel. In the embodiment
described, the following effects occur. Light originating from the
first light source is reflected at the side faces of the prisms of
the first cluster of deformities, while light originating from the
second light source is passed via the upper face and the lower face
of the prisms of the first cluster. It is noted for clarity that
side faces of a prism are situated between the ribs of the prism,
while the upper face and the lower face are situated at the
so-called end faces of the prism. Conversely, light originating
from the second light source is reflected at the side faces of the
prisms of the second cluster of deformities, while light
originating from the first light source is passed via the side
faces of the prisms of this second cluster. If only the first light
source is switched on, then only the deformities forming part of
the first cluster couple light out of the panel, which deformities
thus form the first light symbol and cause it to light up.
Correspondingly, only the deformities forming part of the second
cluster couple light out of the panel, which deformities thus form
the second light symbol and cause it to light up. If both light
sources are switched on, then both clusters of deformities couple
out light, thus forming both light symbols. If, in addition, the
first and the second light sources couple light of different colors
into the panel, then the light symbols having these different
colors light up independently of each other. In this manner, a
luminaire having a great attractive effect and a high attention
value is obtained. By suitably switching on and off the light
sources, a luminaire having dynamic lighting possibilities is
obtained in this manner.
If, for example, the panel of a luminaire is triangular in shape,
with light sources being associated with all three edge surfaces,
and the ribs of the three types of triangular prisms extending
transversely to the direction in which, in operation, the
respective light sources emit light, then also the prisms of the
other two clusters will reflect part of the light emitted by the
first light source. In the case of a triangular panel, it is
advantageous to employ deformities in the form of tetrahedrons.
Each one of the side faces of a tetrahedron is then associated with
one of the edge surfaces of the panel.
It is particularly favorable if the upper face and the lower face
of the prisms are provided in a direction transverse to the rear
wall. By virtue thereof, light which is reflected at the upper or
the lower face of a prism as a result of the transition from or to
such an upper or lower face, is emitted in the same, yet oppositely
directed, direction. In this manner, such light cannot be coupled
out of the panel. It is further very favorable if the side faces of
the prisms exhibit total internal reflection.
The scope of protection of the invention also comprises a
light-emitting panel provided with deformities for use in a
luminaire as described in this description and the claims.
These and other aspects of the invention will be apparent from and
elucidated with reference to the embodiments described
hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1A is a cross-sectional view of an embodiment of a luminaire
in accordance with the invention;
FIG. 1B is a front view of the luminaire shown in FIG. 1A;
FIG. 2A is a cross-sectional view of an alternative embodiment of a
luminaire in accordance with the invention;
FIG. 2B shows a detail of the embodiment of the luminaire shown in
FIG. 2A;
FIG. 3 shows the path of the light rays through a deformity in the
form of a triangular prism.
FIG. 4 is a cross-sectional view of an alternative embodiment of a
luminaire in accordance with the invention;
FIG. 5A is a cross-sectional view of an alternative embodiment of a
luminaire in accordance with the invention;
FIG. 5B is a cross-sectional view of an alternative embodiment of a
luminaire in accordance with the invention;
The Figures are purely diagrammatic and not drawn to scale.
Particularly for clarity, some dimensions are exaggerated strongly.
In the Figures, like reference numerals refer to like parts
whenever possible.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1A is a cross-sectional view of an embodiment of a luminaire
in accordance with the invention. The luminaire comprises a panel 1
of a light-transmitting material. The panel 1 is manufactured, for
example, from a synthetic resin, acryl, polycarbonate, PMMA, for
example Perspex, or glass. Under the influence of total internal
reflection, light is transported through the panel 1, during
operation. The panel 1 has a light emission window 2 and a rear
wall 3 situated opposite said light emission window. Between the
light emission window 2 and the rear wall 3 there are edge surfaces
4, 14. In the example shown in FIG. 1A, the edge surface referenced
4 is light-transmitting, and a light source 5, 5', 5", . . . is
associated with said edge surface.
In this example, the light source 5, 5', 5", . . . comprises a
plurality of light-emitting diodes (LEDs), however, a different
light source is also possible, such as a discharge lamp or, in
general, a plurality of opto-electronic elements, also referred to
as electro-optic elements, such as electroluminescent elements. The
source brightness of LEDs is many times higher than that of
fluorescent tubes. In addition, when use is made of LEDs, the
efficiency with which light is coupled into the panel is higher
than in the case of fluorescent tubes. The use of LEDs as the light
source has the advantage that the LEDs may abut against panels made
of a synthetic resin. LEDs hardly emit heat, nor do they emit
harmful (UV-)radiation. The use of LEDs has the additional
advantage that means for coupling light originating from the LEDs
into the panel are not necessary. The use of LEDs leads to a more
compact luminaire.
To obtain a luminaire having a high attraction value, use can be
made of so-called power packages of LEDs. For example,
high-efficiency, high-output LEDs of the "Barracuda" type
(Hewlett-Packard) can be used. The luminous flux per LED is 15 lm
for red LEDs, 13 lm for green LEDs, 5 lm for blue LEDs and 20 lm
for amber LEDs. The use of these high-efficiency, high-output LEDs
has the specific advantage that the number of LEDs necessary for a
desired, relatively high light output can be relatively small. This
adds to the compactness and the efficiency of the luminaires to be
manufactured. In an alternative embodiment, high-efficiency,
high-output LEDs of the "Prometheus" type (Hewlett-Packard) are
used, in which case the luminous flux per LED is 35 lm for red
LEDs, 20 lm for green LEDs, 8 lm for blue LEDs and 40 lm for amber
LEDs.
By using LEDs as the light source, daylight-viewable luminaires are
obtained whose brightness is comparable to, or better than, the
brightness of a luminaire based on light generated in luminaires on
the basis of fluorescent tubes or neon light.
Preferably, the LEDs are mounted on a metal-core printed circuit
board. If power LEDs are mounted on such a metal-core printed
circuit board (MC-PCB), the heat generated by the LEDs can be
readily dissipated by heat conduction via the PCB. An interesting
embodiment of the luminaire comprises a housing, accommodating the
LEDs, which is made of metal and provided with cooling fins, and,
in said embodiment, the metal-core printed circuit board is in
contact with the metal housing via a heat-conducting connection.
Such a heat-conducting connection is preferably formed by mounting
the MC-PCB on a metal plate which is connected to the metal
housing. The heat generated in the LEDs can be dissipated by means
of (thermal) conduction via the MC-PCB and the metal plate to the
housing and the cooling fins, so that heat is emitted to the
environment. This has the advantage that forced air cooling for
removing heat, as applied in the known luminaire, is not
necessary.
In operation, light originating from the light source 5, 5', 5", .
. . is coupled into the panel 1 via the light-transmitting edge
surface 4, which light spreads in the panel 1. In accordance with
the principle of total internal reflection, the light continues to
move back and forth in the panel 1 unless the light is coupled out
of the panel 1, for example, by a deformity that has been provided.
The edge surface opposite the light-transmitting edge surface 4 is
referenced 14 and is preferably provided with a reflecting coating
(not shown in FIG. 1A) to hold the light originating from the light
source 5, 5', 5", . . . inside the panel. Without this reflecting
coating, an edge surface is obtained having an attractive
appearance. In an alternative embodiment, both opposed edge
surfaces are provided with light sources.
In accordance with the measure of the invention, the panel 1
comprises a plurality of deformities 7, 7', 7", . . . ; 8, 8', . .
. for coupling light out of the panel 1 via the light emission
window 2. In FIG. 1A, the deformities 7, 7', 7", . . . ; 8, 8', . .
. are provided in the rear wall 3 of the light-emitting panel 1. In
an alternative embodiment, the deformities are provided in the
light emission window 2 or, in a different manner, for example on
the outside of the panel 1. In FIG. 1A, two clusters 17; 18 of
deformities 7, 7', 7", . . . ; 8, 8', . . . are indicated. The
deformities 7, 7', 7", . . . ; 8, 8', . . . serve as means for
coupling light out of the panel 1. The deformities 7, 7', 7", . . .
; 8, 8', . . . form optical structures and are preferably provided
with a specularly reflecting coating (see FIG. 3). Particularly
favorable deformities 7, 7', 7", . . . ; 8, 8', . . . are those
where total internal reflection causes light to be coupled out of
the panel 1. In a further alternative embodiment, the deformities
are diffusely reflecting. A suitable combination of specularly and
diffusely reflecting deformities also forms a favorable embodiment
of the invention. By means of said combination, conspicuous light
effects can be achieved. For example, a specularly reflecting light
symbol serving to draw attention may be used in a diffusely
reflecting light symbol.
A deformity in the panel serves as a secondary light source. A
specific optical system may be associated with this secondary light
source, which optical system is provided, for example, on the light
emission window (not shown in FIG. 1A). The optical system may be
used to form a parallel light beam.
FIG. 1A very diagrammatically shows light rays originating from the
light source 5, 5', 5", . . . , which light rays touch the surface
of the deformities 7, 7', 7", . . . ; 8, 8', . . . , causing the
light rays to be reflected at said surface. The reflected light
rays are directed, away from the rear wall 3, towards the light
emission window 2 and are thus coupled out of the panel 1 at the
location of said light emission window 2. The clusters 17; 18 of
deformities 7, 7', 7", . . . ; 8, 8', . . . each form one light
symbol 27; 28, the cluster 17; 18 having a configuration which
corresponds to the shape of the light symbol 27; 28. For clarity,
the light rays in FIG. 1A are drawn so as to be parallel to each
other. In practice, a plurality of directions will travel through
the light-emitting panel. Light can only leave the panel 1 if the
angle of incidence of the light at the light emission window is
smaller than the critical angle.
FIG. 1B shows a front view of the luminaire shown in FIG. 1A, with
a "text" lighting up during operation. Each one of the light
symbols 27; 28 is formed by light originating from a plurality of
LEDs 5, 5', 5", . . . , which light is coupled into the panel 1 via
the edge surface 4, and which light is coupled out by reflecting
deformities 7, 7', 7", . . . ; 8, 8', . . . , which are arranged in
clusters the configuration of which corresponds to the light symbol
27; 28 formed.
FIG. 2A is a cross-sectional view of an alternative embodiment of a
luminaire in accordance with the invention. With respect to FIGS.
1A and 1B, corresponding parts in FIGS. 2A and 2B are indicated by
reference numerals which are 100 higher. The luminaire comprises a
panel 101 having a first light-transmitting edge surface 104 and a
second light-transmitting edge surface 104', each having an
opposing edge surface 114 and 114', respectively, which reflect the
light. A light emission window of the panel 101 corresponds to the
plane of the drawing and, in FIG. 2A, is directed towards an
observer of the panel 101. One first light source, in this example
a plurality of LEDs 105, 105', 105", . . . , is associated with the
first light-transmitting edge surface 104, and one second light
source, in this example a further plurality of LEDs 106, 106',
106", . . . , is associated with the second light-transmitting edge
surface 104'. In accordance with the invention, the luminaire is
capable of making a first collection of light symbols 127, 127',
127", . . . and a second collection of light symbols 128, 128',
128", . . . light up independently. In this example, the first
collection of light symbols 127, 127', 127", . . . jointly form the
word "OPEN", and the second collection of light symbols 128, 128',
128", . . . jointly form the word "CLOSED".
The LEDs may all be a different color. This leads to a further
increase of the attention value of the panel. By choosing, by way
of example, green LEDs for the LEDs with reference numeral 105,
105', 105", . . . , and red LEDs for the LEDs with reference
numeral 106, 106', 106", . . . , the first collection of light
symbols lights up in green and the second collection of light
symbols lights up in red. In other words, during operation, the
word "OPEN", lights up in green and the word "CLOSED" lights up in
red.
FIG. 2B shows a detail of the embodiment of the luminaire
referenced 110 in FIG. 2A, the deformities 107, 107', 107", . . . ;
108, 108', . . . in the panel 101 (see FIG. 2A), which couple out
light for making the collections of light symbols 127, 127', 127",
. . . ; 128, 128', 128", . . . light up, being shown very
diagrammatically. In accordance with the preferred embodiment of
the invention, in operation, a first cluster of deformities 107,
107', 107" couples out light originating from the first light
source 105, 105', 105", . . . to form a first light symbol 127,
127', 127", . . . , while, independently thereof, a second cluster
of deformities 108, 108', . . . , in operation, couples out light
originating from the second light source 106, 106', 106", . . . to
form a second light symbol 128, 128', 128", . . . . The
configurations of the clusters of deformities 107, 107', 107", . .
. ; 108, 108', . . . correspond to the collections of light symbols
127, 127', 127", . . . ; 128, 128', 128", . . . .
In the example shown in FIG. 2B, two different types of deformities
are drawn. One type of deformities 107, 107', 107", . . . is
symbolically drawn as a square with a horizontal line, while the
other type of deformities 108, 108', . . . is symbolically drawn as
a square with a vertical line (also see FIG. 3 and the associated
description).
The shape of the deformities 7, 7', 7", . . . ; 8, 8', . . . ; 107,
107', 107", . . . ; 108, 108', . . . is favorably chosen from the
group formed by a triangular prism, a tetrahedron, a quadrilateral
pyramid and a (truncated) cone. Such shapes are very suitable for
coupling light out of the luminaire in various ways. The upright
side faces of a tetrahedron and of a quadrilateral pyramid (see
FIG. 5) are capable of independently reflecting light originating
from different light sources and of independently coupling it out
of the panel. The number of side faces of such deformities may
depend upon the number of edge surfaces of the panel with which one
or more light sources are associated. By means of a cone (not shown
in the Figures), light originating from all directions can be
coupled out of the panel.
A deformity in the form of a triangular prism is very suitable for
allowing unobstructed passage of light in one direction and
coupling it out of the panel in a direction transverse thereto.
FIG. 3 shows a deformity in the form of a triangular prism 207 and
the path of the light rays through such a prism. The deformity 207
is provided with a side face 2071 in the rear wall 203 of the
panel. The other two side faces extending parallel to the ribs of
the prism 207 are referenced 2072 and 2073 in FIG. 3. In the
embodiment described, the following effects occur. A light ray
travelling in the direction indicated by means of (a) in FIG. 3 is
passed via the upper and the lower face 2074 and 2075 of the prism
and continues on its way through the panel via the light line
indicated by means of (a') in FIG. 3. Light traveling through the
panel in a direction (b), transverse to the direction (a)-(a'), is
incident on the reflecting surface 215 provided on the side faces
2071; 2072 and is reflected thereby, resulting in the formation of
the light ray (b'), which is subsequently coupled out of the panel
in a way as shown in FIG. 1A. If only the light source generating
the light ray (b) is switched on, then the prismatic deformity 207
couples light out of the panel; such a prism, which forms part of a
first cluster of deformities, thus contributes to the lighting up
of a first light symbol. If only the light source generating the
light ray (a) is switched on, then the prismatic deformity 207 does
not couple light out of the panel; in this manner, such a prism
does not contribute to the lighting-up of a first light symbol.
In FIG. 3, the side face boundary surfaces 2072 and 2073 of the
triangular prism deformity 207 are provided with a reflecting
coating 215. In an alternative embodiment, the prisms are formed
such that total internal reflection in the prism causes light to be
coupled out of the panel. The situation wherein the ribs of the
prism do not extend parallel to the rear wall is not excluded.
Furthermore, it may be advantageous if, on a side of the prisms
facing away from the light source, the prisms have a greater height
with respect to the rear wall than on the side of the prisms facing
the light source. The prisms may also be obliquely provided in the
panel in a different way, if desired. By virtue thereof, the
direction in which the light is coupled in by the panel can be
adjusted in accordance with the application or the requirements of
the user. For example, it may further be desirable that light
originating from the first light source is coupled out of the panel
in a different direction than light originating from the second
light source.
The deformities 107, 107', 107", . . . in FIG. 2B are in the form
of a triangular prism, as shown in FIG. 3, having horizontal ribs
with respect to the plane of the drawing, and said deformities
couple out light by reflection if the LEDs 105, 105', 105", . . .
are switched on, thereby contributing to the lighting up of the
light symbol 127 which forms the letter "O" of the word "OPEN" in
FIG. 2A. The deformities 108, 108', . . . in FIG. 2B are in the
form of a triangular prism having vertical ribs with respect to the
plane of the drawing, and said deformities couple out light if the
LEDs 106, 106', 106", . . . are switched on, thereby contributing
to the lighting up of the light symbol 128 which forms the letter
"C" of the word "CLOSED" in FIG. 2A. If both light sources 105,
105, 105", . . . ; 106, 106', 106", . . . are switched on, then
both collections of clusters of deformities 107, 107', 107", . . .
; 108, 108', . . . couple out light, resulting in the formation of
both collections of light symbols 127, 127', 127", . . . ("OPEN")
and 128, 128', 128", . . . ("CLOSED").
The apex of the prism shown in FIG. 3 may be flat, and the upper
face may have a light-scattering effect. The prisms may
alternatively be obliquely arranged with respect to the rear wall
of the panel.
By suitably switching light sources on and off, by changing the
color of the light sources switched-on, by providing suitable
optical systems and by making various lighting symbols light up
alternately and/or sequentially, a luminaire having dynamic
lighting possibilities is obtained. By suitably mixing various
colors also white light can be obtained.
A preferred embodiment of the luminaire comprises control
electronics for changing the luminous flux of the light-emitting
diodes 5, 5', 5", . . . , 6, 6', 6", . . . ; 105, 105', 105", . . .
, 106, 106', 106", . . . . In this manner, a luminaire having a
high attractive effect and a high attention value is obtained.
FIG. 4 is a diagrammatic, cross-sectional view of an alternative
embodiment of a luminaire in accordance with the invention. With
respect to FIG. 2A, corresponding parts in FIG. 4 are indicated by
reference numerals which are 200 higher. The luminaire comprises a
panel 301 with a housing 302. In this example, the light source
comprises a linear array of differently colored LEDs which are
alternately arranged, i.e. red LEDs referenced 305, yellow LEDs
referenced 305' and green LEDs referenced 305". The luminaire is
capable of making a combination of two light symbols 327, 328 light
up, which jointly form an arrow. By switching on LEDs of one
specific color, the arrow lights up in this color. In this example,
the arrow can light up in red, yellow or green, so that the arrow
can very suitably be used for traffic applications, for example in
traffic lights.
FIG. 4 diagrammatically shows deformities 307, 307', 307", . . . ;
308, 308', 308" . . . provided in the panel 301, which couple out
light for making the light symbols 327, 328 light up. The
deformities 307, 307', 307"; 308, 308', 308" . . . are in the form
of a triangular prism, as shown in FIG. 3, having horizontal ribs
with respect to the plane of the drawing, and said deformities
couple out light by reflection if the LEDs 305, 305', 305" are
switched on, causing the light symbols 327, 328 to light up.
By alternately switching on and off various colored light sources,
the light symbols light up in various colors. As a result thereof,
a luminaire in accordance with the invention has dynamic lighting
possibilities with a high attention value.
FIG. 5A is a diagrammatic, cross-sectional view of a further
alternative embodiment of a luminaire in accordance with the
invention. With respect to FIG. 4, corresponding parts in FIG. 5A
are indicated by reference numerals which are 100 higher. The
luminaire comprises a panel 401 with a housing 420, 420'. In this
example, the light source comprises a linear array of red LEDs 405,
405', 405". The luminaire is capable of making a light symbol 427
light up, which light symbol represents a stationary person. By
switching on the red LEDs 405, 405', 405", said person lights up in
this color. As a result, the luminaire can very suitably be used
for traffic applications, in particular as a red traffic light at
pedestrian crossings ("do not cross").
FIG. 5A diagrammatically shows deformities 407, 407', 407" provided
in the panel 401, which couple out light for making the light
symbol 427 light up. The deformities 407, 407', 407" are in the
form of a triangular prism, as shown in FIG. 3, having horizontal
ribs with respect to the plane of the drawing, and said deformities
couple out light by reflection if the LEDs 405, 405', 405" are
switched on, causing the light symbol 427 to light up.
FIG. 5B is a diagrammatic, cross-sectional view of a further
alternative embodiment of a luminaire in accordance with the
invention. With respect to FIG. 5A, corresponding parts in FIG. 5B
are indicated by reference numerals which are 100 higher. The
luminaire comprises a panel 501 with a housing 520, 520'. A first
light source, in this example a plurality of green LEDs 505, 505',
is provided in a part of the housing bearing reference numeral 520.
A second light source, in this example a further plurality of LEDs
506, 506', 506", 506'", is provided in a further part of the
housing bearing reference numeral 520'. In operation, the LEDs 505,
505' and the LEDs 506, 506', 506", 506'" emit light in two mutually
perpendicular directions.
In the example shown in FIG. 5B, the luminaire comprises three
different light symbols, referenced 527, 528 and 529, which, in
operation, jointly form a person who seems to be walking.
Deformities 507, 507', 507" couple out light for making the light
symbol 427 light up. The deformities 507, 507', 507" are in the
form of a triangular prism, as shown in FIG. 3, having horizontal
ribs with respect to the plane of the drawing, and said deformities
couple out light by reflection if the LEDs 505, 505' are switched
on, causing the light symbol 527 to light up, which represents a
person's right leg. Deformities 508, 508', 508" couple out light
for making the light symbol 428 light up. The deformities 508,
508', 508" are in the form of a triangular prism, as shown in FIG.
3, having vertical ribs with respect to the plane of the drawing,
and said deformities couple out light by reflection if the LEDs
506, 506' are switched on, causing the light symbol 528 to light
up, which represents the person's left leg. Deformities 509, 509',
509" couple out light for making the light symbol 529 light up,
which represents the upper part of the person's body. The
deformities 509, 509', 509" are in the form of a quadrilateral
pyramid, indicated in FIG. 5B as a square wherein a cross is drawn.
The quadrilateral pyramids are provided at right angles to the
plane of the drawing, the ribs of the base being alternately
provided transversely to the directions wherein, in operation, the
LEDs 505, 505'; 506, 506', 506", 506'" emit light. The deformities
509, 509', 509" couple out light by reflection if the LEDs 505,
505' are switched on as well as if the LEDs 506, 506' are switched
on. In either case, they make the light symbol 529 light up.
The luminaire shown in FIG. 5B can very suitably be used for
traffic applications, in particular as a green traffic light at
pedestrian crossings ("safe to cross the street"). In operation,
the LEDs 506", 506'" are continuously switched on, and the LEDs
505, 505' and the LEDs 506, 506' are alternately switched on. If
the LEDs 505, 505' are switched on, the person's right leg is
lifted, and if the LEDs 506, 506' are switched on, the person's
left leg is lifted. A suitably chosen alternation results in a
person who seems to be walking while lighting up green. If the
luminaire is in operation, the LEDs 506", 506'" do not have to be
switched on continuously. By suitably switching and taking into
account the overlap between the on-periods, the light symbols 527,
528 and 529 are jointly capable of producing an attractive
rendition of a person who seems to be walking. In this manner, the
luminaire in accordance with the invention has dynamic lighting
possibilities with a high attention value.
It will be obvious that, within the scope of the invention, many
variations are possible to those skilled in the art.
The scope of protection of the invention is not limited to the
examples given herein. For example, the panel does not have to be
rectangular. The number of edge surfaces of the panel may be more
than four, for example six or eight. The panel of the luminaire may
be round or oval, if so desired, having light sources arranged in
suitable positions. These edge surfaces may be associated with the
differently placed and/or differently colored light sources. The
shape of the deformities is adapted to the shape of the panel. In
this manner, a plurality of patterns of luminescent and colored
light symbols can be obtained.
The scope of protection of the invention is not limited to the
examples given herein. The invention is embodied in each novel
characteristic and each combination of characteristics. Reference
numerals in the claims do not limit the scope of protection
thereof. The use of the verb "to comprise" and its conjugations
does not exclude the presence of elements or steps other than those
stated in the claims. The use of the article "a" or "an" in front
of an element does not exclude the presence of a plurality of such
elements.
* * * * *